The present invention relates to a new type of sector mold for tires.
The conventional molds consist of several separate parts which, when brought together, define a quasi-toroidal molding space. They essentially have two shells for the molding of the tire walls and a plurality of peripheral sectors located between the shells for the molding of the tread. The bringing together of all these parts is assured by a suitable kinematic system by means of a suitable mechanism. The raw blank of the future tire must be firmly applied and held against the mold in order to obtain precise geometrical dimensions and architecture and in order, if necessary, to impress the sculpturing in the tread. As a result, the blank exerts a substantial pressure on the parts of the mold, which pressure (referred to as internal pressure) tends to open the mold and, therefore, to separate its parts.
There are known systems which hold the mold firmly closed by the combined or separate action of hydraulic or pneumatic jacks and mechanical wedging parts, such as for example peripheral rings, which transfer the resting onto the structure of the press via the mold closing mechanism. In order to obtain quality manufacture, it is necessary to develop substantial closing force. Therefore, all the parts which assure the kinematic system of the mold must be dimensioned so as not to suffer deformation. As a result of this, a mold-press unit is a heavy and expensive machine.